The turbine of an airplane turbojet has combustion gas that is very hot passing therethrough and therefore operates under temperature conditions that are particularly difficult. Thus, the fastener hooks which are in contact with the combustion gas stream are subjected to much greater heating is the jacket which, in any event, is cooled on its outside face by a cooling system, generally a system of perforated pipes, commonly referred to as “shower collars”, blowing cool air onto said jacket.
As shown in European patent application EP 1 288 444, it is known to make such fastener hooks out of an alloy that is good at withstanding high temperatures and that might possibly differ depending on the locations of said hooks inside the jacket; it is also known to make the jacket out of a more ordinary alloy, an alloy that is less refractory than that of the hooks, and that is therefore easier and less expensive to form.
In that known embodiment, the hooks are fastened to the jacket by an interference fit, by conventional welding, or by bolting. Those various assembly methods nevertheless present drawbacks.
For example, conventional welding with melting encourages hot cracking in the melt zone and the appearance of cracks in the zone that is thermally affected during welding. Bolting complicates the structure of the casing and increases the number of parts making it up. And none of those assembly means generally presents satisfactory resistance to fatigue.